Water is routinely tested for the presence of Cryptosporidium and Giardia. Detection relies on immunofluorescence techniques to stain cysts and oocysts with a green fluorescent dye. The stained sample is examined using epifluorescent microscopy and the number of green fluorescing cysts and oocysts recorded.
The methodology involves numerous processes is which cysts and oocysts can be lost. It is, therefore, important to perform stringent quality control to monitor the performance of the methodology. At present, quality control is an external process that involves analysing a standard that contains a known number of cysts and oocysts. Such a quality control test is typically performed after analysing 10 or 20 samples. This external quality control is far from ideal. Losses of cysts and oocysts can very greatly between different samples. Some samples may be unsuitable for analysis. Furthermore, if the quality control result is poor then all results from the 10 or 20 samples must be discarded.
The same situation applies to diagnostic analysis in a wide variety of fields, where an external quality control is subject to the relevant diagnostic analysis being applied as a measure of performance/accuracy.
A need accordingly exists for accurate, convenient, cost-effective, and repeatable quality control in diagnostic analysis, which is currently not met by the prior art.